With an inverter circuit, a snubber circuit is connected in parallel with a switching element, in order, when the switching element is turned off, to prevent surge voltage from being applied to the switching element due to the operation of leakage inductance between the primary side and the secondary side of a transformer. Furthermore, it has also been proposed to provide a regeneration circuit which regenerates charge which has been charged into a snubber capacitor of the snubber circuit to the power supply. By providing this regeneration circuit, this charge is not dissipated as heat by a snubber resistor, and moreover it is possible to improve the efficiency of the inverter circuit, since the energy for charging the snubber capacitor is regenerated to the power supply.
The inverter disclosed in Patent Document #1 is one which, as described above, is provided with a snubber circuit and a regeneration circuit. In the circuit of this inverter, a first switching element and a second switching element are connected to the primary side. The snubber circuit is connected in parallel with the first switching element. Moreover, the regeneration circuit is connected between the snubber circuit and the power supply. The snubber circuit consists of a series circuit of a snubber diode and a snubber capacitor. And the regeneration circuit consists of a series circuit of a switching element for regeneration, a reactor, and a diode for regeneration. A snubber circuit and a regeneration circuit are connected to the second switching element as well, in a similar manner.
With the inverter circuit described above, a control unit turns the first switching element and the second switching element on and off alternatingly, so that the switching element for regeneration is turned on for just a fixed time period. When the switching element for regeneration is turned on, the charge which is charged into the snubber capacitor is discharged perfectly, and is regenerated to the power supply.    Patent Document #1: Japanese Laid-Open Patent Publication 2003-219653.